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Inductive effect
The permanentdisplacement of sigma (σ) electrons along a saturated chain, whenever anelectron withdrawing or electron donating group is present, is called inductiveeffect.
Inductive effect couldbe + I effect or – I effect. When an atom or group attracts electrons towardsitself more strongly than hydrogen, it is said to possess – I effect. Forexample,
When an atom or groupattracts electrons towards itself less strongly than hydrogen, it is said topossess + I effect. For example,
Electrometric effect
It involves the completetransfer of the shared pair of π electrons to either of the two atoms linked bymultiple bonds in the presence of an attacking agent. For example,
Electrometric effectcould be + E effect or – E effect.
+ E effect: When the electronsare transferred towards the attacking reagent
– E effect: When the electrons aretransferred away from the attacking reagent
(a) Cl3CCOOH> Cl2CHCOOH > ClCH2COOH
The order of acidity canbe explained on the basis of Inductive effect (– I effect). As the number ofchlorine atoms increases, the – I effect increases. With the increase in – Ieffect, the acid strength also increases accordingly.
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(b) CH3CH2COOH> (CH3)2 CHCOOH > (CH3)3 C.COOH
The order of acidity canbe explained on the basis of inductive effect (+ I effect). As the number ofalkyl groups increases, the + I effect also increases. With the increase in + Ieffect, the acid strength also increases accordingly.
